• Journal of The Korean Association For Science Education
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• v.36 no.4
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• pp.607-616
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• 2016

In the 2009 revised science curriculum, comprehensive verbs such as 'know (38%)' and 'understand (46%)' are used in more than 80% of the achievement standard. Many readers, such as teachers, textbook makers, etc. have difficulties in interpreting the meaning of achievement standard sentences with these comprehensive verbs. On the other hand, 'Trends in International Mathematics and Science Study (TIMSS)' uses more various and specific verbs to express the cognitive domain. In this study, we analyzed the 2009 revised science curriculum achievement standard focusing on the TIMSS cognitive domain assessment framework. We divided achievement standard to 228 sentences and three teachers analyzed the meaning of verbs in achievement standard. There were two main results of this study. First, the verb 'Know' was analyzed into different kinds of meanings, such as 'Describe (27%)', 'Recall/Recognize (25%)' and 'Relate (17%)', etc; and the verb 'Understand' was analyzed into 'Explain (37%)', 'Relate (27%)' and 'Describe (21%)', etc. Second, there appeared to have a disagreement among the three analysts during the process of interpreting the achievement standards when the level and scope of the contents of each grade is not clear. This study concludes that there's a need for continuous discussion on the use of verbs in achievement standard to promote clearer expressions for better understanding.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.9
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• pp.387-396
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• 2020

The purpose of this study is to identify the variables of metropolitan and provincial offices of education that affect the academic achievement of unit schools, and to predict how academic achievements dynamically change with the support of offices of education. The results of academic achievement of 606 general high schools in 16 metropolitan and provincial offices of education(rates of attaining more than normal education in Korean, English, and mathematics subjects) were analyzed using a multi-level model and system dynamics. As a result of the analysis, it was confirmed that the provincial and provincial offices of education's efforts to increase the efficiency of local education finance, the efforts to reduce teacher administration, and the facilitation of faculty training were the variables of the provincial and provincial offices of education. In addition, through policy experiments, efforts to revitalize teacher training were the most influential factors in academic achievement of unit schools, followed by efforts to streamline local education finances and to reduce the administrative work of teachers. In order to improve the academic achievement of unit schools, the functions of the metropolitan and provincial offices of education should be strengthened based on the education accountability, and policies need to be established in the mid- to long-term perspective.

• Journal of the Korean earth science society
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• v.39 no.6
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• pp.600-616
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• 2018

The purpose of this study was to explore how primary school students develop their interest in science. A survey questionnaire was used to investigate students' interest, change of their interest, and engagement in science related activities three times a year. 201 students of two primary schools in Seoul Metropolitan City initially participated in this study. A follow-up case study was conducted with students who showed an increased interest in science. Finally, seven students were chosen in the case study. They were asked to keep a photo journal for 12 weeks, and were interviewed in every other week by one of the researchers. Among these seven participants, two (TK and QQ) were chosen for analyzing their data in this case study because they showed positive changes in developing science interest throughout the study. The results of two participants' survey, photo-journal and interview were analyzed qualitatively. First, TK, whose science interest developed from situational interest II to individual interest I, engaged in doing experiments at home, doing mathematics activities, raising pets or plants, observing phenomena, and visiting informal educational centers. He tended to participate in hands-on activities by himself in out-of-school settings. Second, QQ who developed from situational interest I to situational interest II, engaged in taking pictures as a representative activity at home and school. He tended to participate in activities with either his father or one of the researchers. Both students showed personal characteristics such as doing place-based activities, interaction with others and activity subjectivity. The goal of TK's interactions with others on the various places was to develop in cognitive domain. On the contrary, QQ's goal of interactions with others was to develop in emotional communication. This study reported the cases of characteristics of students who developed their interests in science including activities in- and out-of-school settings and their accompanying people.

• Clean Technology
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• v.22 no.3
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• pp.190-195
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• 2016

The thermal decomposition of waste energetic materials such as TNT, RDX and composition B in a commercial rotary kiln has previously been carried out. As part of the demilitarization process, the thermal decomposition of homogeneous double base propellant (DB) used in M8 and consisting predominantly of nitrocellulose and nitroglycerine is examined with respect to a number of operating conditions. A single condensed phase reaction with 4 species and 365 gas phase reactions and 59 species are considered. Simulation results show the sensitivity of the thermal decomposition of DB with temperature and velocity. At relatively low velocity with constant inlet hot air temperature, temperature in the rotary kiln was found to be highest, 953 K and 1300 K for cases 3 and 6 respectively. Illustrating that optimum operating temperature can be achieved by controlling the inlet velocity without additional cooling systems.

• Journal of KIISE:Software and Applications
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• v.31 no.1
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• pp.54-60
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• 2004

Face recognition is one of the problems to be solved by appearance based matching technique. However, the appearance of face image is very sensitive to variation in illumination. One of the easiest ways for better performance is to collect more training samples acquired under variable lightings but it is not practical in real world. ]:n object recognition, it is desirable to focus on feature extraction or normalization technique rather than focus on classifier. This paper presents a simple approach to normalization of faces subject to directional illumination. This is one of the significant issues that cause error in the face recognition process. The proposed method, ICR(illumination Compensation based on Multiple Linear Regression), is to find the plane that best fits the intensity distribution of the face image using the multiple linear regression, then use this plane to normalize the face image. The advantages of our method are simple and practical. The planar approximation of a face image is mathematically defined by the simple linear model. We provide experimental results to demonstrate the performance of the proposed ICR method on public face databases and our database. The experimental results show a significant improvement of the recognition accuracy.

• Journal of the Korea Concrete Institute
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• v.14 no.6
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• pp.813-822
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• 2002

The purpose of the present study is first to refine the mathematical material models for moisture and temperature distributions in early-age concrete and then to incorporate those models into finite element procedure. The three dimensional finite element program developed in the present study can determine the degree of hydration, temperature and moisture distribution in hardening concrete. It is assumed that temperature and humidity fields are fully uncoupled and only the degree of hydration is coupled with two state variables. Mathematical formulation of degree of hydration Is based on the combination of three rate functions of reaction. The effect of moisture condition as well as temperature on the rate of reaction is considered in the degree of hydration model. In moisture transfer, diffusion coefficient is strongly dependent on the moisture content in pore system. Many existing models describe this phenomenon according to the composition of mixture, especially water to cement ratio, but do not consider the age dependency. Microstructure is changing with the hydration and thus transport coefficients at early ages are significantly higher because the pore structure in the cement matrix is more open. The moisture capacity and sink are derived from age-dependent desorption isotherm. Prediction of a moisture sink due to the hydration process, i.e. self-desiccation, is related to autogenous shrinkage, which may cause early-age cracking in high strength and high performance concrete. The realistic models and finite element program developed in this study provide fairly good results on the temperature and moisture distribution for early-age concrete and correlate very well with actual test data.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.2
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• pp.167-174
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• 2010

In this study, the optimal position for the backrest pivot of an office chair was investigated by evaluating its performance in terms of the lumbar support and sliding distance of the back from the backrest during tilting motions. The simulation was performed using a mathematical model, which included a human body and a chair. Forty-two backrest pivot points were selected on the sagittal plane around the hip joint of a sitting model. A motion analysis study was also performed using a prototype of an office chair (A-type) with a backrest pivot located on the hip joint of a normal Korean model and a typical office chair (B-type) with its pivot located under the seat. The simulation results showed that both the lordosis angle and the slide distance of the back were minimized when the backrest pivot was positioned close to the hip joint. The experimental results showed that the slide distance and gap between the sitter's lumbar and the backrest was smaller with the A-type than the B-type. Based on the simulation and experimental results, it can be concluded that the backrest can support the sitter's lumbar area more effectively as the pivot position for reclining approaches closer to the hip joint. In this position, the sitter can maintain a comfortable and healthy sitting posture. This paper presents the methods and guidelines for designing an office chair with ergonomic considerations.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.23 no.2
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• pp.75-81
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• 2017

Modified atmosphere packaging (MAP) of vacuum, 60% $N_2/40%$ $CO_2$, 100% $N_2$ and 100% $CO_2$ were examined to preserve fried fish cakes and extend their shelf life. When product packages in air were stored at 5, 10, and $15^{\circ}C$ with measurement in quality attributes, aerobic bacterial growth was found to be primary quality factor to determine the shelf life of the product. Huang's model was adopted to obtain the parameters for use in shelf life determination for a variety of packaging and storage conditions. Temperature dependence expressed in Arrhenius equation showed activation energies of 139.4 and 41.8 kJ/mol for inverse of lag time and growth rate of the microbial spoilage, respectively. MAP of 100% $CO_2$ could double the product shelf life at $10^{\circ}C$ compared to air package. High $CO_2$ concentration MAP at low temperature was found to be effective to prolong the shelf life.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.6
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• pp.106-112
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• 2017

This paper presents a mathematical model derived from the upper-bound theorem of concrete plasticity to rationally evaluate the shear friction strength of concrete interfaces with a construction joint. The upper limit of the shear friction strength was formulated from the limit state of concrete crushing failure on the strut-and-tie action along the construction joints to avoid overestimating the shear transfer capacity of a transverse reinforcement with a high clamping force. The present model approach proposed that the cohesion and coefficient of friction of concrete can be set to be $0.27(f_{ck})^{0.65}$ and 0.95, respectively, for rough construction joints and $0.11(f_{ck})^{0.65}$ and 0.64, respectively, for smooth ones, where $f_{ck}$ is the compressive strength of concrete. From the comparisons with 155 data compiled from the available literature, the proposed model gave lower values of standard deviation and coefficient of variation of the ratios between predictions and experiments than AASHTO and fib 2010 equations, indicating that the proposed model has consistent trends with test results, unlike the significant underestimation results of such code equations in evaluating the shear friction strength.

• Korean Chemical Engineering Research
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• v.45 no.3
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• pp.242-248
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• 2007

For an optimal design of automotive electric system, it is important to have a reliable modeling tool to predict the charge-discharge behaviors of the automotive battery. In this work, a two-dimensional modeling was carried out to predict the charge-discharge behaviors of a 12-V automotive lead-acid battery. The model accounted for electrochemical kinetics and ionic mass transfer in a battery cell. In order to validate the modeling, modeling results were compared with the experimental data of the charge-discharge behaviors of a lead-acid battery. The discharge behaviors were measured with three different discharge rates of C/5, C/10, and C/20 at operating temperature of $25^{\circ}C$. The batteries were charged with constant current of 30A until the charging voltage reached to a predetermined value of 14.24 V and then the charging voltage was kept constant. The discharge and charge curves from the measurements and modeling were in good agreement. Based on the modeling, the distributions of the electrical potentials of the solid and solution phases, the porosity of the electrodes, and the current density within the electrodes as well as the acid concentration can be predicted as a function of charge and discharge time.